1. Field of the Invention
The present invention relates to an image display apparatus for spatially modulating light emitted from a light source and displaying the spatially modulated light on a screen, more particularly to an image display apparatus and method that enable a three-dimensional (3D) video signal to be displayed.
2. Description of the Related Art
Recently, the size of the screens of display apparatus has been increasing. Micro device displays, for example, have established a strong presence in the large-screen display market because their structure, in which light emitted from a light source is spatially modulated and projected through a projection lens onto a screen, facilitates increased screen area, and they take advantage of the excellent image display performance of the micro display devices used for spatial modulation, such as digital mirror devices (DMDs), high temperature polysilicon (HTPS) devices, and liquid crystal on silicon (LCOS) devices.
The traditionally popular content displayed on large screens is movies and sports. Recently, however, there has been an increasing need for the display of three-dimensional video (3D video) such as three-dimensional movies and three-dimensional video games.
A known method of displaying three-dimensional video with a micro device display is disclosed in, for example, Japanese Tokuhyo Publication No. 2007-531473 (Published Japanese translation of PCT International Publication WO 2005/099279).
The method described in Japanese Tokuhyo Publication No. 2007-531473 is problematic in that light from the light source is sequentially filtered by a color filter wheel to obtain specific colors and three-dimensional glasses having left and right lenses that transmit light of different wavelengths are used to view the spatially modulated light, so the amount of light entering the observer's eyes is cut in half in comparison with the amount emitted from the light source; consequently, the picture is darkened.
In this method, the input video signal is separated into sub-frames for left-eye and right-eye images and the sub-frames are displayed sequentially. With this method, however, if the input video signal has the generally used rate of 60 Hz, the micro display device must switch and display the left-eye and right-eye images at a rate of at least 120 Hz. Since the response speeds of liquid crystal devices such as HIPS and LCOS devices are low, if the left-eye and right-eye images are switched at a high speed for 3D display, there is a possibility that residual images of a frame previously displayed may be seen, that is, crosstalk may occur.
The video signal displayed on the display has generally undergone picture quality enhancement processing, such as noise processing and edge enhancement, in order to compensate for noise arising in the signal transmission system and for reduction in resolution due to bandwidth restriction. However, there is a problem in that if the same uniform pixel-to-pixel filtering process as used for a two-dimensional video signal is carried out on a 3D video signal having left-eye and right-eye images in one frame of the input signal, unwanted filtering will be performed across the left and right image data, degrading the quality of the image when displayed as a 3D video picture.
When liquid crystal devices such as HIPS and LCOS devices are employed, overdrive processing is indispensable to improve motion response. There is also a problem in that when a video signal with a frame rate doubled due to sub-frame separation for three-dimensional display undergoes overdrive processing, a large bus bandwidth is required for frame memory access, increasing the cost.